A motor control center, also referred to as an MCC, is generally a cabinet-like structure that is divided into modular sections designed to accept a plurality of component motor control center units, also referred to as MCC units. An MCC unit is generally a drawer-like container of electrical components, such as circuit breakers, motor starters, relays, power meters, programmable logic controllers, and other control circuit components used for electrical power distribution in industrial and commercial applications. The MCC unit slides into an MCC section and plugs into a common power bus running vertically along the back side of the MCC section. The MCC unit includes a connector, also referred to as a stab assembly or stabs, arranged on the back side of the unit, to plug into the power bus.
When an MCC unit is serviced, it is of utmost importance to prevent the operator from being exposed to electrical shocks and arc flash hazards, collectively “electrical hazards.” In existing motor control center units, such as is disclosed in the prior art U.S. Pat. No. 8,199,022, electrical feed-through terminals on the front panel of a motor control center unit, convey test signals from internal test points, to enable troubleshooting without opening the front panel. When not in use, the patent describes that the terminals may be covered by a metal arc flash resistant cover. However, there is no flexibility in expanding or modifying the test point terminals without drilling or machining the front panel of the prior art MCC unit. Moreover, there is no provision for installing or modifying pilot devices in the front panel of the prior art motor control center unit, such as pilot lights, push buttons, selector switches, or other control devices.